Methods of Forming Patterns

ABSTRACT

Some embodiments include methods of forming patterns. A first mask is formed over a material. The first mask has features extending therein and defines a first pattern. The first pattern has a first level of uniformity across a distribution of the features. A brush layer is formed across the first mask and within the features to narrow the features and create a second mask from the first mask. The second mask has a second level of uniformity across the narrowed features which is greater than the first level of uniformity. A pattern is transferred from the second mask into the material.

TECHNICAL FIELD

Methods of forming patterns.

BACKGROUND

Integrated circuit fabrication often involves formation of patternedmasks across materials, followed by transfer of patterns from the maskinto the materials. For instance, patterned masks may be utilized forfabrication of memory, logic, etc.

A continuing goal is to increase density of integrated circuitry. Arelated goal is to increase density of features within patterned masks.However, difficulties may be encountered in attempting to createuniform, dense patterns of features within masks. Accordingly, it isdesired to develop new methods of forming patterned masks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are diagrammatic top views of a semiconductor constructionat process stages of an example embodiment.

FIGS. 3 and 4 are diagrammatic top views of a semiconductor constructionat process stages of another example embodiment.

FIGS. 5-13 are diagrammatic top views of a semiconductor construction atprocess stages of another example embodiment. FIGS. 5A-13A arediagrammatic cross-sectional side views along the lines A-A of FIGS.5-13, respectively.

FIG. 14 is a diagrammatic top view of a semiconductor construction at anexample process stage following that of FIG. 13, and FIG. 14A is adiagrammatic cross-sectional side view along the line A-A of FIG. 14.

FIG. 15 is a diagrammatic top view of a semiconductor construction at ananother example process stage following that of FIG. 13, and FIG. 15A isa diagrammatic cross-sectional side view along the line A-A of FIG. 15.

FIG. 16 is a diagrammatic top view of a semiconductor construction atanother example processing stage which may follow that of FIG. 10. FIG.16A is a diagrammatic cross-sectional side view along the line A-A ofFIG. 16.

FIG. 17 is a diagrammatic top view of a semiconductor construction at anexample processing stage following that of FIG. 16. FIG. 17A is adiagrammatic cross-sectional side view along the line A-A of FIG. 17.

FIGS. 18-20 are diagrammatic cross-sectional side views of asemiconductor construction at various processing stages of anotherexample embodiment.

FIG. 21 is a top view (a) and a side view (b) of a patterned substratetreated in accordance with Example 2.

FIG. 22 is a top view (a) and a side view (b) of a patterned substratetreated in accordance with Example 3.

FIG. 23 is a top view of a patterned substrate treated in accordancewith Example 4.

FIG. 24 is a top view of a patterned substrate treated in accordancewith Example 5.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments include methods of utilizing a brush layer to improveuniformity across a population of patterned features. The term “brushlayer” is utilized herein to refer to a layer formed by covalent bondingof a polymeric organic material to a surface. In some embodiments, thebrush layer may comprise a siloxane; and may be formed from asiloxane-containing precursor such as, for example, a precursorcomprising poly(dimethylsiloxane) (PDMS). In some embodiments, the brushlayer may be formed from precursors comprising other organic polymerseither in addition to, or alternatively to, siloxane-containingpolymers. For example, the brush layer may be formed utilizingprecursors comprising one or both of polystyrene (PS) andpoly(methylmethacrylate) (PMMA). The brush layer precursors have one ormore substituents substituents suitable for reacting with surfaces tothereby covalently bond (i.e., graft) the brush layer to the surfaces.Such substituents may comprise hydroxyl moieties, sulfhydryl moieties,etc.

An example utilization of a brush layer to improve uniformity across apopulation of patterned features is described with reference to FIGS. 1and 2.

Referring to FIG. 1, a portion of a construction 10 is shown in topview. The construction comprises rings 12 of masking material 14 formedacross an upper surface of a base 15. The rings 12 touch one another,and form two sets of openings over base 15. One set corresponds tocircular openings 16 within the middle of the rings, and another setcorresponds to diamond-shaped openings 18 bounded by four adjacent ringstouching one another. In some embodiments, the rings 12 may beconsidered to form a first mask over base 15, with the openings 16 and18 corresponding to first features extending through the first mask anddefining a first pattern. Such first pattern has a first level ofuniformity across a distribution of the features 16 and 18, and suchlevel of uniformity is low due to the openings 18 being of significantlydifferent shape relative to the openings 16.

Referring next to FIG. 2, a brush layer 20 is formed to be selectivelyon material 14 (FIG. 1) relative to the material of base 15, and suchnarrows openings 16 and 18. The formation of brush layer 20 may beconsidered to form a second mask from the first mask of FIG. 1. Suchsecond mask has a greater level of uniformity than did the first maskdue to differences between the shapes of openings 16 and 18 beingalleviated through formation of the brush layer. Specifically, the brushlayer has partially filled openings 16 and 18, and smoothed thedifferences between such openings. The smoothing may result, at least inpart, from the brush layer achieving a thermodynamically-favored balanceof surface tension and other forces whereby hydrophobic chains of thebrush layer assemble together in a manner which substantially optimizesthe diminished free energy from minimizing surface area with theincreased free energy from chain stretching to achieve a substantiallylowest overall free energy. Such forms substantially circular peripheralpatterns along interiors of the openings due to substantially circularperipheral patterns having less surface area than other peripheralpatterns (with the term “substantially circular” meaning circular towithin reasonable tolerances of fabrication and measurement). Insubsequent processing, the pattern of openings 16 and 18 may betransferred into base 15.

Another example utilization of a brush layer to improve uniformityacross a population of patterned features is described with reference toFIGS. 3 and 4.

Referring to FIG. 3, a portion of a construction 30 is shown in topview. The construction comprises patterned masking material 32 formedacross an upper surface of the base 15. The masking material hasfeatures 34 corresponding to openings which extend through the maskingmaterial. Such openings have irregular peripheral surfaces. Adistribution of shapes and sizes across the population of openings 34has a low level of uniformity due to the irregular peripheral surfacesof the openings.

Referring next to FIG. 4, brush layer 20 is formed to be selectively onmasking material 34 (FIG. 3) relative to the material of base 15. Thebrush layer narrows openings 34 while reducing irregularities across theperipheral surfaces. The formation of brush layer 20 may be consideredto form a second mask from the first mask of FIG. 3. The second mask ofFIG. 4 has a greater level of uniformity across the population ofopenings 34 than does the first mask of FIG. 3. In processing subsequentto the stage of FIG. 4, the pattern of openings 34 may be transferredinto base 15.

In the embodiments of FIGS. 1-4, the uniform features formed in thesecond masks (the features 16 and 18 in the mask of FIG. 2, and thefeatures 34 in the mask of FIG. 4) have substantially circularperipheries. In other embodiments, other feature shapes may be formed.For instance, if the original patterns in the mask are more elongatedthan the illustrated features, then the features formed utilizing thebrush layer may be elongated rather than being circular.

There are numerous applications in which it is desired to form a maskhaving a high level of uniformity across a population of features. Anexample embodiment is described with reference to FIGS. 5-13.

Referring to FIGS. 5 and 5A, a construction 50 comprises a semiconductorbase 52 having a stack 54 thereover. The stack comprises acarbon-containing material 58 over an electrically insulative material56. Photoresist 62 is over the stack 54, and in the shown embodiment isspaced from such stack by a deposited antireflective coating (DARC) 60.

The base 52 may comprise semiconductor material, and in some embodimentsmay comprise, consist essentially of, or consist of monocrystallinesilicon. In some embodiments, base 52 may be considered to comprise asemiconductor substrate. The term “semiconductor substrate” means anyconstruction comprising semiconductive material, including, but notlimited to, bulk semiconductive materials such as a semiconductive wafer(either alone or in assemblies comprising other materials), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure, including, but not limited to, the semiconductor substratesdescribed above. In some embodiments, base 52 may correspond to asemiconductor substrate containing one or more materials associated withintegrated circuit fabrication. Some of the materials may be under theshown region of base 52 and/or may be laterally adjacent the shownregion of base 52; and may correspond to, for example, one or more ofrefractory metal materials, barrier materials, diffusion materials,insulator materials, etc.

The base 52 may support integrated circuitry in some embodiments. Forinstance, an upper region of base 52 may comprise an array of conductivenodes (not shown), and processing of FIGS. 5-13 may be utilized to forma pattern suitable for forming electrically conductive contacts to suchconductive nodes. As another example, an upper region of base 52 maycomprise semiconductor material, and processing of FIGS. 5-13 may beutilized to form a pattern suitable for forming conductively-dopedimplant regions within such conductive material. As yet another example,the base 52 may support a memory array (for instance, a flash memoryarray, a DRAM array, etc.), and the processing of FIGS. 5-13 may beutilized to form a pattern suitable for aligning electrically conductivecontacts to individual memory cells.

The electrically insulative material 56 may comprise any suitablecomposition or combination of compositions; and in some embodiments maycomprise an inorganic oxide and/or an inorganic nitride. For instance,in some embodiments material 56 may comprise, consist essentially of, orconsist of one or both of silicon dioxide and silicon nitride.

The carbon-containing material 58 may comprise, consist essentially of,or consist of carbon. For instance, in some embodiments the material 58may consist of transparent carbon.

The DARC 60 may comprise any suitable composition or combination ofcompositions; and in some embodiments may comprise, consist essentiallyof, or consist of silicon oxynitride. Suitable materials for DARC 60 mayinclude materials having appropriate optical properties (e.g., n+kvalues at 193 nanometers) and chemical properties (e.g., a surface whichcan graft with brush layer precursor).

The photoresist 62 may be any suitable composition.

Referring to FIGS. 6 and 6A, an arrangement of openings 64 is formedwithin photoresist 62 through appropriate photolithographic processing.The illustrated openings 64 are example features, and other featureshapes may be formed in other embodiments.

Referring to FIGS. 7 and 7A, the openings 64 are widened. In theillustrated embodiment the openings 64 are widened to an extent thatthey touch one another. In other embodiments, the openings may bewidened to a lesser extent so that they do not touch one another. In yetother embodiments, the openings may be widened to a greater extent sothat they merge with one another. In some embodiments, the arrangementof openings of FIGS. 6 and 6A may be considered to be a firstarrangement of openings formed within photoresist, and the widenedopenings of FIGS. 7 and 7A may be considered to be a second arrangementof openings within the photoresist.

Referring to FIGS. 8 and 8A, the openings 64 are lined with spacermaterial 66. The spacer material has a surface which reacts with brushlayer precursor. In some embodiments, such surface may comprise oxygen,and the spacer material may be referred to as an oxygen-containing film.For instance, the spacer material may comprise one or more inorganicoxides; such as, for example, one or more of silicon dioxide, siliconoxynitride, aluminum oxide, etc. The spacer material conformally coatsthe photoresist 62 to create a configuration having an undulatingtopography across an upper surface of construction 50. The spacermaterial may be formed utilizing any suitable methodology, including,for example, atomic layer deposition.

In some embodiments, the spacer material may be initially formed tocomprise a surface lacking oxygen, and then oxygen may be introducedalong such surface utilizing oxidative conditions; such as, for example,an oxidative plasma.

In some embodiments, the spacer material may have a surface comprisingone or more other elements from group 16 of the periodic table inaddition to, or alternatively to, oxygen. For instance, the spacermaterial may have a surface comprising one or more of sulfur, selenium,etc.

Referring to FIGS. 9 and 9A, the spacer material 66 is anisotropicallyetched to form spacers 68. The spacers 68 are configured as annularrings in the shown configuration.

Openings 64 extend through the central regions of the ring-shapedspacers 68 to expose an upper surface of DARC material 60. Also,photoresist 62 (visible in FIGS. 7 and 7A) is removed to form anotherset of openings 70 that are outside of the ring-shaped spacers 68. Theopenings 64 may be considered to correspond to a first set of openings,and the openings 70 may be considered to correspond to a second set ofopenings; with the openings of the first set having a different shapethan the openings of the second set. In some embodiments, spacers 68 maybe considered to form a first mask over stack 54, with such first maskhaving a first level of uniformity across a population of openings. Suchpopulation comprises a distribution containing openings 64 of a firstshape, and openings 70 of a second shape.

Although the shown embodiment forms spacers 68 through a singledeposition and etch of spacer material, in other embodiments multipledepositions and/or etches of spacer material may be utilized to tailorwidths of the spacers 68. Further, additional depositions of spacermaterial may alleviate some of the heterogeneity between openings 64 and70, and thereby increase uniformity across the distribution of theopenings.

Referring to FIGS. 10 and 10A, the pattern from spacers 68 istransferred through DARC material 60 to expose an upper surface ofcarbon-containing material 58. In some embodiments, the materials 60 and66 may be considered together to form a first mask overcarbon-containing material 58.

Referring to FIGS. 11 and 11A, a brush layer 20 is selectively formed onexposed surfaces of materials 60 and 66 relative to a surface ofcarbon-containing material 58. The brush layer reduces heterogeneitybetween the shapes of openings 64 and 70.

In some embodiments, the brush layer may be formed from a polymericprecursor having appropriate reactive moieties which react with oxygen(and/or other elements from group 16 of the periodic table) alongexposed surfaces of materials 60 and 66 to from covalent bonds to suchexposed surfaces. For instance, in some embodiments the brush layerprecursor may comprise one or more of PS, PDMS and PMMA, withappropriate reactive groups, such as, for example, hydroxyl, sulfhydryl,etc. An advantage of utilizing a siloxane in the brush layer is thatsuch may enable the carbon-containing material 58 to be selectivelyremoved relative to the brush layer in subsequent processing (discussedbelow). PDMS is one example of a polymeric organic siloxane, in otherembodiments the brush layer may comprise other polymeric organicsiloxanes; and in some embodiments may comprise polymers containingcarbon and silicon, with at least 17% silicon content (by atomic mass).

In some embodiments, the brush layer may comprise PDMS consisting ofpolymers within a molecular weight range of from about 5,000 atomic massunits to about 110,000 atomic mass units.

In some embodiments, the brush layer may comprise PDMS and may beselectively bonded to one or both of silicon dioxide and siliconoxynitride relative to carbon.

Processing utilized to form the brush layer may comprise exposing theconstruction of the type shown in FIGS. 10 and 10A to brush layerprecursor under conditions which enable covalent bonding (for instance,a condensation reaction) between the precursor and exposedoxygen-containing surfaces. The conditions may include baking of theconstruction at a temperature of from about room temperature to about350° C. (for brush polymers having reactive hydroxyl moieties which bondto 60/66; e.g., PDMS with hydroxyl moieties). After the brush layer isformed, a rinse may be conducted to remove excess precursor.Subsequently, the brush layer may be heated to a temperature above aglass transition temperature (T_(g)) to enable the brush layer toachieve a thermodynamically-favored state which minimizes surface area,and which thereby reduces heterogeneity across a distribution ofopenings.

In some embodiments, the brush layer 20 together with materials 60 and66 may be considered to form a mask 72 across an upper surface ofcarbon-containing material 58. Such mask comprises openings 64 and 70which are narrowed relative to the openings shown in the mask of FIGS.10 and 10A. However, the openings 64 and 70 of the mask of FIGS. 11 and11A are approximately the same size and shape as one another.Accordingly, differences between the shapes of openings 64 and 70 havebeen alleviated, and the mask of FIGS. 11 and 11A has a higher level ofuniformity than the mask of FIGS. 10 and 10A.

In the shown embodiment of FIGS. 11 and 11A, brush layer 20 is formedselectively along materials 60 and 66 relative to carbon-containingmaterial 58. Accordingly, the carbon-containing material remains exposedat the bottoms of openings 64 and 70 after formation of the brush layer.

The various materials 60, 66 and 58 are example materials. In someembodiments, analogous materials may comprise compositions other thanthose specifically described for materials 60, 66 and 58. In someembodiments, materials 66 and 68 may be referred to as first materials,and material 58 as a second material, and the brush layer may beconsidered to be selectively formed on the first materials relative tothe second material. In other embodiments, the brush layer may formalong surfaces of all of the first and second materials, and thenanisotropic etching may be utilized to remove the brush layer from overthe surface of material 58 and thereby expose the surface of material 58at the bottoms of openings 64 and 70 (an analogous embodiment isdescribed below with reference to FIGS. 18-20).

The embodiment of FIGS. 5-11 utilizes a brush layer to improveuniformity across a mask having openings with different shapes relativeto one another. In other embodiments, openings may be formed underconditions such that the openings have irregularities across peripheralsurfaces (analogous to the irregularities described above with referenceto FIG. 3), and brush layer processing may be utilized to alleviateheterogeneity across the population of such openings.

Referring to FIGS. 12 and 12A, the openings 64 and 70 are extendedthrough material 58 (i.e., are transferred through material 58) toexpose an upper surface of the electrically insulative material 56.

Referring to FIGS. 13 and 13A, the openings 64 and 70 are extendedthrough electrically insulative material 56 (i.e., are transferredthrough material 56) to expose an upper surface of the semiconductorbase 52, and materials 58, 60, 66 and 20 are removed with one or moresuitable etches.

The materials 58, 60, 66 and 20 are removed at the processing stage ofFIGS. 13 and 13A in the shown embodiment. In other embodiments one ormore of such materials may remain at the processing stage of FIGS. 13and 13A, and at other processing stages subsequent that of FIGS. 13 and13A.

Referring to FIGS. 14 and 14A, electrically conductive material 80 isformed within openings 64 and 70 and patterned into a series ofelectrically conductive contacts extending to an upper surface of base52. The electrically conductive material 80 may comprise any suitablecomposition or combination of compositions; and in some embodiments maycomprise, consist essentially of, or consist of one or more of variousmetals (for example, tungsten, titanium, etc.), metal-containingcompositions (for instance, metal nitride, metal carbide, metalsilicide, etc.), and conductively-doped semiconductor materials (forinstance, conductively-doped silicon, conductively-doped germanium,etc.). In some embodiments, material 80 may be deposited to overfillopenings 64 and 70, and then excess material may be removed bychemical-mechanical polishing (CMP) or other suitable planarization toform the construction shown in FIGS. 14 and 14A. In some embodiments,the electrically conductive contacts may extend to an array ofelectrically conductive nodes (not shown) present on an upper surface ofbase 52.

FIGS. 14 and 14A illustrate an example processing stage that may followformation of openings 64 and 70. In other embodiments, the openings maybe utilized for other processing associated with integrated circuitfabrication. For instance, the pattern of openings 64 and 70 may betransferred into the semiconductor base 52 by etching into the base toform recesses extending into the base and/or to pattern materialsassociated with the base. As another example, the pattern of openings 64and 70 may be transferred into the semiconductor base 52 by implantingdopant through the openings to form dopant implant regions withinlocations defined by the openings. For instance, FIGS. 15 and 15A showconstruction 50 at a processing stage subsequent to that of FIGS. 13 and13A in an embodiment in which dopant is implanted through the openingsto form implant regions 84 within semiconductor base 52. In someembodiments, an upper surface of base 52 may comprise silicon, and theimplanted dopant may be either n-type or p-type dopant utilized to formconductively-doped regions 84.

Although the embodiment of FIGS. 11 and 11A forms the brush layer onmaterials 66 and 60, in other embodiments the spacer material 66 may beremoved prior to formation of the brush layer. The brush layer may thenbe formed selectively on silicon oxynitride material 60 relative to theunderlying carbon-containing material 58. An example of such processingis described with reference to FIGS. 16 and 17.

FIGS. 16 and 16A show construction 50 at a processing stage which mayfollow that of FIGS. 10 and 10A, and specifically show material 66removed to leave the patterned material 60 over carbon-containingmaterial 58.

Referring next to FIGS. 17 and 17A, brush layer 20 is selectively formedacross exposed surfaces of silicon oxynitride 60 relative to exposedsurfaces of carbon-containing material 58, which reduces differencesbetween openings 64 and 70. Processing analogous to the variousprocesses described above with reference to FIGS. 12-15 may be conductedsubsequent to the processing stage of FIGS. 17 and 17A.

As discussed above with reference to FIGS. 11 and 11A, in someembodiments a brush layer may be formed non-selectively over multiplematerials, and then anisotropically etched to form features (forinstance, spacers) suitable for subsequent process stages. FIGS. 18-20illustrate an example embodiment in which a brush layer is formednon-selectively across multiple materials.

Referring to FIG. 18, a construction 100 is shown to comprise apatterned second material 104 over a first material 102. The first andsecond materials may be compositionally different from one another.

Referring to FIG. 19, a brush layer 20 is formed non-selectively alongsurfaces of materials 104 and 102. In some embodiments, the surfaces ofmaterials 102 and 104 may comprise oxygen, and the brush layer may beformed by reaction of a brush layer precursor with suchoxygen-containing surfaces.

Referring to FIG. 20, the brush layer is anisotropically etched to formspacers 106. Such spacers may then be utilized for subsequent processinganalogous to processing described above with reference to previousfigures of this disclosure. (In other embodiments, not shown, the brushlayer 20 may selectively form only on material 104 at the processingstage of FIG. 19, in which case the anisotropic etch of FIG. 20 may beomitted.)

In some embodiments, it may be desired to chemically modify a brushlayer to alter chemical characteristics of the brush layer and therebyimprove suitability of the brush layer as a hardmask. For instance, insome embodiments the brush layer may comprise a silicon-containingpolymer (which may comprise, for example, at least about 17 percentsilicon [by atomic mass]), and it may be desired to incorporate oxygeninto the brush layer. In some embodiments, the chemical modification maybe conducted prior to the anisotropic etch described in FIG. 20, and insome embodiments the chemical modification may be conducted after aselective deposition analogous to that described above with reference toFIGS. 11 and 11A. A deposition analogous to that of FIGS. 11 and 11A mayinclude a selective deposition along a masking material analogous tomaterial 66 to leave a surface exposed (analogous to the surface ofmaterial 58) wherein the exposed surface may or may not be acarbon-containing material. In some embodiments, the chemicalmodification may comprise exposure of a brush layer to O₂ plasma toconvert the brush layer to an oxide film. Such exposure may shrink andsmooth brush-layer-lined openings in some applications.

In some embodiments, organic brush layers may be utilized to formspacers. For instance, an organic brush layer (for instance,polystyrene) may be applied to SiO₂ features (like the features 68 ofFIGS. 9 and 9A in some embodiments), and then the SiO₂ features may beremoved to leave spacers comprising the organic material of the brushlayer. Thus, organic material of a brush layer may form spin-on spacersin some embodiments.

Unless specified otherwise, the various materials, substances,compositions, etc. described herein may be formed with any suitablemethodologies, either now known or yet to be developed, including, forexample, atomic layer deposition (ALD), chemical vapor deposition (CVD),physical vapor deposition (PVD), etc.

The terms “dielectric” and “electrically insulative” are both utilizedto describe materials having insulative electrical properties. Bothterms are considered synonymous in this disclosure. The utilization ofthe term “dielectric” in some instances, and the term “electricallyinsulative” in other instances, is to provide language variation withinthis disclosure to simplify antecedent basis within the claims thatfollow, and is not utilized to indicate any significant chemical orelectrical differences.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. The descriptionprovided herein, and the claims that follow, pertain to any structuresthat have the described relationships between various features,regardless of whether the structures are in the particular orientationof the drawings, or are rotated relative to such orientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections in order to simplifythe drawings.

When a structure is referred to above as being “on” or “against” anotherstructure, it can be directly on the other structure or interveningstructures may also be present. In contrast, when a structure isreferred to as being “directly on” or “directly against” anotherstructure, there are no intervening structures present. When a structureis referred to as being “connected” or “coupled” to another structure,it can be directly connected or coupled to the other structure, orintervening structures may be present. In contrast, when a structure isreferred to as being “directly connected” or “directly coupled” toanother structure, there are no intervening structures present.

Some embodiments include a method of forming a pattern. A first mask isformed over a material. The first mask has features extending thereinand defining a first pattern. The first pattern has a first level ofuniformity across a distribution of the features. A brush layer isformed across the first mask and within the features to narrow thefeatures and to create a second mask from the first mask. The secondmask has a second level of uniformity across the narrowed features whichis greater than the first level of uniformity. A pattern is transferredfrom the second mask into the material.

Some embodiments include a method of forming a pattern. A stack isformed over a semiconductor substrate. The stack comprises carbon overan electrically insulative material. A first mask is formed over thecarbon. The first mask has openings extending therein with the openingsdefining a first pattern. The first pattern has a first level ofuniformity across a distribution of the openings. A brush layer isformed across the first mask and within the openings to narrow theopenings and create a second mask from the first mask. The brush layeris selectively formed along material of the first mask relative to thecarbon. The second mask has a second level of uniformity across thenarrowed openings which is greater than the first level of uniformity. Apattern is transferred from the second mask through the carbon and theelectrically insulative material.

Some embodiments include a method of forming a pattern. Patternedphotoresist is formed to have a plurality of spaced-apart openingsextending therethrough. The openings are widened. A spacer material isdeposited within widened openings. The spacer material isanisotropically etched and the photoresist is removed. The anisotropicetching forms spacers from the spacer material. The spacers are annularrings and are a first mask having a pattern extending therethrough whichhas two shapes of openings. A brush layer is formed across the spacermaterial and within the openings to alleviate differences between thetwo shapes and form a second mask from the first mask. A pattern istransferred from the second mask into a second material under the secondmask.

Some examples are provided below to assist the reader in understandingsome aspects of the invention. The specific parameters of the examplesare not to limit the invention in any way, except to the extent, if any,that such parameters are expressly recited in the claims which follow.

EXAMPLES

The following materials were passed through a column packed withactivated A-2 grade alumina before being used in the specific Examples1-5 described below; namely tetrahydrofuran (THF), (99.9% pure availablefrom Aldrich), styrene (available from Aldrich), and cyclohexane (HPLCgrade available from Fischer). Hydroxyl-terminatedpoly(dimethylsiloxane) (PDMS-OH) with M_(n)=10 kg/mol andM_(w)/M_(n)=1.10 was purchased from Gelest and used as received. All theother materials used in the specific Examples 1-5 described below werecommercial materials that were used as received.

The number average molecular weight, M_(N), and polydispersity valuesreported in Examples 1-5 were measured by gel permeation chromatography(GPC) on an Agilent 1100 series liquid chromatography (LC) systemequipped with an Agilent 1100 series refractive index and MiniDAWN lightscattering detector (Wyatt Technology Co.). Samples were dissolved inHPLC grade THF at a concentration of approximately 1 mg/mL and filteredthrough a 0.20 μm syringe filter before injection through the two PLGel300×7.5 mm Mixed C columns (5 mm, Polymer Laboratories, Inc.). A flowrate of 1 mL/min and temperature of 35° C. were maintained. The columnswere calibrated with narrow molecular weight PS standards (EasiCal PS-2,Polymer Laboratories, Inc.).

Proton nuclear magnetic resonance (¹H NMR) spectroscopy results referredto in the Examples that follow was done on a Varian INOVA 400 MHz NMRspectrometer using a delay time of 10 seconds to ensure completerelaxation of protons for quantitative integrations. Chemical shifts arereported relative to tetramethylsilane.

Example 1 PDMS-OH Synthesis

Trimethylsilyl lithium silanolate (0.060 g, 0.62 mmol) was weighed intoa 20 mL vial and dissolved in 2 g dry THF. Next, freshly sublimedhexamethyl(cyclotrisiloxane) monomer (D3, 9.7 g, 44 mmol) was weighedinto a 200 mL jar and then dissolved in 48 g THF. The lithium silanolatesolution was added to the D3 solution along with a stir bar, and thecontents were left stirring at room temperature (RT) for 1 h beforequenching with ˜½ mL chlorodimethyl silane. The reaction mixture wasstirred overnight and then precipitated into 600 mL MeOH. The MeOH wasdecanted away, leaving a viscous liquid which was air dried overnight,and then dried further overnight in a vacuum oven at 60° C. to yield 6.8g of Si—H terminated PDMS with Mn˜14,600 g/mol as determined by NMR. Toconvert the Si—H terminated PDMS to PDMS-OH, the Si—H terminated PDMS(4.0 g) and allyl alcohol (0.29 g, 4.9 mmol, 18 eq. based on silane)were combined in a 20 mL vial. The vial was placed under a blanket ofN₂, and a small scoop of 5% Pt/C was added to it. The vial was cappedand heated to 110° C. for 15 h in a heating block. Analysis by ¹H NMRfollowing the reaction showed complete conversion of the silane. Thecrude reaction mixture was filtered through a frit and 1 μm filter usinghexanes to remove the residual Pt/C catalyst. The polymer was isolatedby drying at 60° C. under vacuum.

Example 2 Substrate Preparation and Imaging

A pattern of SiO₂ lines on a carbon floor were prepared using standardlithographic and etch techniques. Small coupons were cut from the waferand used as the substrate in Example 2. Before treatment, a coupon wasevaluated by microscopy after mounting on a 25 mm×6 mm aluminum samplestub with the aid of double-sided carbon tape. Top-down scanningelectron microscopic (SEM) images were recorded by a Hitachi CG4000 SEM(Hitachi Co., Japan) operating at 0.2 to 2 kV accelerating voltage and400,000 magnifications. Cross section (SEM) images were recorded by aHitachi S-4800 FE-SEM (Hitachi Co., Japan) operating at 15 kVaccelerating voltage and 400,000 magnifications. Critical dimension(CD), line width roughness (LWR), and line edge roughness (LER) valueswere measured using Hitachi's Terminal PC Data Processing Software,V5.04˜, and Terminal PC Offline CD Measurement Software, V5.03˜, and arereported as the average values from 5 images. Representative images areshown in FIG. 21. The incoming patterned substrate had lines with avertical profile and CD=15 nm, LWR 3σ=2.9 nm, and LER 3σ=5.2 nm.

Example 3 PDMS-OH Brush Grafting

A solution of PDMS-OH was prepared by dissolving the PDMS-OH in heptaneto form a 1.3 wt % solution. The solution was hand filtered through a0.2 μm Whatman syringe filter, and the product filtrate material wasused to coat the patterned coupon. A thin film of the PDMS-OH was formedon the patterned substrate by spin coating the solution using conditionsthat gave a 21 nm film on an unpatterned silicon substrate as measuredusing a NanoSpec/AFT 2100 Film Thickness Measurement tool, followed by asoft bake at 150° C. for 60 seconds to remove residual solvent. Thecoated substrate was then subjected to a second bake at 250° C. for 120seconds to induce grafting. Residual ungrafted PDMS-OH was then removedby washing with a puddle of heptane and spin-drying, followed by anothersoft bake at 150° C. for 60 seconds to remove residual solvent. Thecoupon was then evaluated by microscopy after mounting on a 25 mm×6 mmaluminum sample stub with the aid of double-sided carbon tape. Top-downscanning electron microscopic (SEM) images were recorded by a HitachiCG4000 SEM (Hitachi Co., Japan) operating at 0.2 to 2 kV acceleratingvoltage and 400,000 magnifications. Cross section (SEM) images wererecorded by a Hitachi S-4800 FE-SEM (Hitachi Co., Japan) operating at 15kV accelerating voltage and 400,000 magnifications. Critical dimension(CD), line width roughness (LWR), and line edge roughness (LER) valueswere measured using Hitachi's Terminal PC Data Processing Software,V5.04˜, and Terminal PC Offline CD Measurement Software, V5.03˜, and arereported as the average values from 5 images. Representative images areshown in FIG. 22. After PDMS-OH treatment, the lines on the substrateincreased in CD, were noticeably smoother, and maintained a verticalprofile without footing. The lines were characterized with CD=28 nm, LWR3σ=1.4 nm, and LER 3σ=2.5 nm.

Example 4 Substrate Preparation and Imaging

A pattern of SiON crowns was prepared by first forming a patternedphotoresist having a plurality of spaced-apart holes using standardlithographic techniques. The holes were then widened and a SiON spacermaterial was deposited within the widened openings. The substrate wasthen anistropically etched to remove the photoresist to form a patternof annular rings with two shapes of openings. Small coupons were thencut from the wafer and used as the substrate in Example 2. Beforetreatment, a coupon was evaluated by microscopy after mounting on a 25mm×6 mm aluminum sample stub with the aid of double-sided carbon tape. ADenton Vacuum DV-502A plasma coater was used to sputter a coating ofiridium (4 nm) in order to render the sample conductive under theelectron beam. Top-down scanning electron microscopic (SEM) images wererecorded by an AMRAY 4200 operated at 15 kV under a working distance of˜10 mm. The images were analyzed using ImageJ software. A representativeimage is shown in FIG. 23. The pattern consisted of annular rings withtwo shapes of openings, round holes corresponding to the original holesin the photoresist and diamond-shaped holes in the regions around thecrowns where adjacent crowns converge and touch one another. The roundholes measured 34.7±1.5 nm, while the average end-to-end distance of thediamond shaped holes measured 32.3±1.4 nm.

Example 5 PDMS-OH Brush Grafting

A solution of PDMS-OH (0.8 wt %) was prepared in heptanes and filteredthrough a Teflon filter having a 0.2 μm pore size. The filtered solutionwas coated on a coupon of the crown template from Example 4 by spincoating at 1500 rpm. The coated wafer was then annealed under N₂ at 300°C. for 120 seconds. The substrate was then treated to remove unreactedPDMS-OH by washing twice with heptane using the following process:puddling heptane on the wafer, allowing it to sit for 60 seconds,spinning the wafer dry at 3000 rpm over 60 seconds, repeating thisheptane puddling process, and then baking the substrate to removeresidual heptane at 150° C. for 60 seconds. The treated coupon was thenevaluated by microscopy after mounting on a 25 mm×6 mm aluminum samplestub with the aid of double-sided carbon tape. A Denton Vacuum DV-502Aplasma coater was used to sputter a coating of iridium (4 nm) in orderto render the sample conductive under the electron beam. Top-downscanning electron microscopic (SEM) images were recorded by an AMRAY4200 operated at 15 kV under a working distance of ˜10 mm. The imageswere analyzed using ImageJ software. A representative image is shown inFIG. 24. After treatment, the holes are smaller and more uniform in size(28.0±1.3 nm) and have no discernible difference in shape as the brushprocess effectively rounded the convex diamond-shaped holes into roundholes.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1. A method of forming a pattern, comprising: forming a first mask overa material, the first mask having features extending therein anddefining a first pattern; the first pattern having a first level ofuniformity across a distribution of the features; forming a brush layeracross the first mask and within the features to narrow the features andcreate a second mask from the first mask; the second mask having asecond level of uniformity across the narrowed features which is greaterthan the first level of uniformity; and transferring a pattern from thesecond mask into the material.
 2. The method of claim 1 wherein thefirst mask comprises a surface containing one or more elements fromgroup 16 of the periodic table, and wherein the brush layer is formedthrough covalent bonding of one or more of polymeric organic siloxanesto the surface through such elements.
 3. The method of claim 1 whereinthe mask comprises an oxygen-containing surface, and wherein the brushlayer is formed through reaction of precursor comprising one or more ofpolystyrene, poly(dimethylsiloxane) and poly(methylmethacrylate) withthe oxygen-containing surface.
 4. The method of claim 1 wherein: thematerial consists of carbon; the first mask comprises anoxygen-containing surface; and the brush layer is formed throughreaction of precursor comprising poly(dimethylsiloxane) with theoxygen-containing surface.
 5. The method of claim 4 wherein thepoly(dimethylsiloxane) consists of polymers within a molecular weightrange of from about 5,000 atomic mass units to about 110,000 atomic massunits.
 6. The method of claim 1 wherein the features of the first maskare distributed amongst two or more different shapes, and wherein thebrush layer alleviates differences between such shapes.
 7. The method ofclaim 1 wherein the features of the first mask have irregular peripheralsurfaces, and wherein the brush layer reduces irregularities across theperipheral surfaces.
 8. The method of claim 1 wherein the transferringcomprises an etch of the material.
 9. The method of claim 1 wherein thetransferring comprises an implant of dopant into the material.
 10. Themethod of claim 1 wherein the narrowed features of the second mask areopenings having substantially circular peripheries.
 11. The method ofclaim 1 further comprising chemically modifying the brush layer prior tothe transferring.
 12. The method of claim 11 wherein the chemicallymodification comprises exposure of the brush layer to oxygen.
 13. Themethod of claim 11 wherein the chemically modification comprisesexposure of the brush layer to O₂ plasma.
 14. A method of forming apattern, comprising: forming a stack over a semiconductor substrate, thestack comprising carbon over an electrically insulative material;forming a first mask over the carbon, the first mask having openingsextending therein with the openings defining a first pattern; the firstpattern having a first level of uniformity across a distribution of theopenings; forming a brush layer across the first mask and within theopenings to narrow the openings and create a second mask from the firstmask; the brush layer being selectively formed along material of thefirst mask relative to the carbon; the second mask having a second levelof uniformity across the narrowed openings which is greater than thefirst level of uniformity; and transferring a pattern from the secondmask through the carbon and the electrically insulative material. 15.The method of claim 14 wherein the openings of the first mask aredistributed amongst two or more different shapes, and wherein the brushlayer alleviates differences between such shapes.
 16. The method ofclaim 14 wherein the openings of the first mask have irregularperipheral surfaces, and wherein the brush layer reduces irregularitiesacross the peripheral surfaces.
 17. The method of claim 14 wherein thefirst mask comprises an inorganic oxide.
 18. The method of claim 14wherein the first mask comprises silicon dioxide.
 19. The method ofclaim 14 wherein the first mask comprises silicon oxynitride.
 20. Themethod of claim 14 wherein the first mask comprises photoresistconformally coated with an oxygen-containing film.
 21. The method ofclaim 14 wherein the first mask comprises photoresist conformally coatedwith silicon dioxide or silicon oxynitride.
 22. The method of claim 14wherein the electrically insulative material comprises silicon dioxide.23. The method of claim 14 wherein the forming of the first maskcomprises: photolithographically patterning photoresist to form a firstarrangement of openings within the photoresist; widening the openings ofthe first arrangement to form a second arrangement of openings; andlining openings of the second arrangement with a spacer material havinga reactive surface which reacts with brush layer precursor; the linedopenings being the first pattern of openings of the first mask.
 24. Themethod of claim 23 wherein the reactive surface comprises oxygen. 25.The method of claim 23 wherein the reactive surface is formed by plasmaoxidation of a surface of the spacer material.
 26. The method of claim14 comprising silicon oxynitride over the carbon, and wherein theforming of the first mask comprises: photolithographically patterningthe photoresist to form a first arrangement of openings within thephotoresist; widening the openings of the first arrangement to form asecond arrangement of openings; lining openings of the secondarrangement with a spacer material to form the first pattern ofopenings; and transferring the first pattern through the siliconoxynitride to thereby form the first mask to comprise the siliconoxynitride having the first pattern of openings extending therethrough.27. The method of claim 14 further comprising filling the openings withelectrically conductive material.
 28. The method of claim 14 furthercomprising extending the openings into the semiconductor substrate. 29.The method of claim 14 further comprising implanting dopant through theopenings and into the semiconductor substrate.
 30. A method of forming apattern, comprising: forming patterned photoresist having a plurality ofspaced-apart openings extending therethrough; widening the openings;depositing a spacer material within widened openings, and thenanistropically etching the spacer material and removing the photoresist;the anisotropic etching forming spacers from the spacer material; suchspacers being annular rings and being a first mask having a patternextending therethrough which has two shapes of openings; forming a brushlayer across the spacer material and within the openings to alleviatedifferences between the two shapes and form a second mask from the firstmask; and transferring a pattern from the second mask into a secondmaterial under the second mask.
 31. The method of claim 30 wherein acarbon-containing material is between the photoresist and the secondmaterial; wherein the carbon-containing material is exposed at bottomsof the openings as the brush layer is formed; wherein the brush layer isformed to be selectively on the spacer material relative to thecarbon-containing material; and wherein the pattern is transferredthrough the carbon-containing material and into the second material. 32.The method of claim 31 wherein the spacer material comprises silicondioxide or silicon oxynitride.
 33. The method of claim 32 wherein thebrush layer is formed from precursor comprising polymeric organicsiloxane.
 34. The method of claim 32 wherein the brush layer is formedfrom precursor comprising poly(dimethylsiloxane).
 35. The method ofclaim 30 wherein the second material is an electrically insulativematerial form over a semiconductor base, and wherein the pattern istransferred through the second material and to the semiconductor base.